Magnetic resonance apparatus with a free-running receive chain and method for operation

Abstract

A magnetic resonance apparatus and a method for operation of the magnetic resonance apparatus are provided. The magnetic resonance apparatus includes a local coil for acceptance and transmission of magnetic resonance signals to the magnetic resonance apparatus. A delay of the magnetic resonance signal between receipt by the local coil and arrival at the magnetic resonance apparatus is variable. In one act of the method, the magnetic resonance apparatus establishes a delay of the magnetic resonance signal between the local coil and the magnetic resonance apparatus and, in a further act, carries out a signal processing process of the transmitted magnetic resonance signal depending on the delay established.

1 . A magnetic resonance apparatus comprising:
 a controller; and   a local coil configured for acceptance and transmission of magnetic resonance signals to the controller,   wherein a delay of a magnetic resonance signal of the magnetic resonance signals between receipt by the local coil and arrival at the controller is variable, the controller being configured to establish the delay,   wherein the controller is further configured to carry out a signal processing process of the transmitted magnetic resonance signal depending on the delay established.   
     
     
         2 . The magnetic resonance apparatus of  claim 1 , wherein the controller is further configured to establish the delay using a calibration measurement. 
     
     
         3 . The magnetic resonance apparatus of  claim 1 , wherein the local coil comprises an encoder configured to impress a time stamp into the magnetic resonance signal, and the controller comprises a decoder configured to decode the time stamp. 
     
     
         4 . The magnetic resonance apparatus of  claim 1 , wherein the controller is further configured to:
 send out a synchronization signal with a time stamp; and   receive the synchronization signal via the local coil and evaluate the time stamp.   
     
     
         5 . The magnetic resonance apparatus of  claim 1 , wherein the signal processing process is a time-dependent mid-frequency correction. 
     
     
         6 . The magnetic resonance apparatus of  claim 1 , wherein the controller is configured to detect the transmitted magnetic resonance signal in a time window depending on the delay established. 
     
     
         7 . The magnetic resonance apparatus of  claim 1 , wherein the controller comprises a buffer configured to compensate for the delay. 
     
     
         8 . A magnetic resonance apparatus comprising:
 a controller;   a local coil configured for acceptance and transmission of magnetic resonance signals to the controller; and   a central clock,   wherein a delay of a magnetic resonance signal of the magnetic resonance signals between the controller and the local coil is variable,
 wherein the local coil comprises a local clock, and the controller is configured to synchronize the local clock with the central clock, 
   wherein the controller is further configured to carry out a magnetic resonance measurement depending on the local clock.   
     
     
         9 . The magnetic resonance apparatus of  claim 8 , wherein the local coil is configured to undertake a mid-frequency correction of a received magnetic resonance signal depending on the local clock. 
     
     
         10 . The magnetic resonance apparatus of  claim 8 , wherein the local coil is configured to detect the magnetic resonance signal in a time window depending on the local clock. 
     
     
         11 . The magnetic resonance apparatus of  claim 8 , wherein the controller comprises a buffer for the magnetic resonance signal. 
     
     
         12 . The magnetic resonance apparatus of  claim 8 , wherein the local coil comprises an encoder for a time stamp in a received magnetic resonance signal, and the controller comprises a decoder configured for decoding the time stamp. 
     
     
         13 . A method for operating a magnetic resonance apparatus, wherein the magnetic resonance apparatus comprises a controller and a local coil, the local coil being configured for acceptance and transmission of magnetic resonance signals to the controller, wherein a delay of a magnetic resonance signal of the magnetic resonance signals between receipt by the local coil and arrival at the controller is variable, the method comprising:
 establishing the delay of the magnetic resonance signal between the local coil and the controller; and   carrying out a signal processing process of the transmitted magnetic resonance signal depending on the delay established.   
     
     
         14 . The method of  claim 13 , wherein establishing the delay comprises a calibration measurement, wherein the calibration measurement comprise:
 creating a test signal with a predetermined delay by the magnetic resonance apparatus;   detecting the test signal with the local coil and the controller;   determining the variable delay from a time difference between the creating of the test signal and the detecting of the test signal by the controller.   
     
     
         15 . The method of  claim 14 , wherein the test signal is a magnetic resonance signal of a sample. 
     
     
         16 . A method for operation of a magnetic resonance apparatus, wherein the magnetic resonance apparatus comprises a controller and a local coil configured for acceptance and transmission of magnetic resonance signals to the controller, the magnetic resonance apparatus further comprising a central clock and the local coil comprising a local clock, wherein a delay of a signal between the controller and the local coil is variable, the method comprising:
 synchronizing the local clock with the central clock; and   carrying out an image acquisition step depending on the local clock.   
     
     
         17 . The method of  claim 16 , wherein the synchronizing comprises sending a synchronization message to the local coil,
 wherein the synchronization message includes information about a current time of the central clock and about a message delay in the controller.   
     
     
         18 . The method of  claim 17 , wherein the local coil includes information about a message delay in the local coil, and
 wherein the synchronizing comprises setting the local clock to a value equal to the current time of the central clock in the synchronization message plus the message delay in the controller plus the message delay in the local coil.